1. Field of the Invention
The present invention relates to a three-dimensional (3D) display device and method using a hybrid position-tracking system, and more particularly, to a 3D display device and method using a hybrid position-tracking system capable of tracking a posture (orientation) change of a mobile display device providing a 3D image using a camera and a gyroscope.
2. Description of the Related Art
A 3D image display device is a device separating an image for a left eye (LE) and an image for a right eye (RE) having binocular parallax and providing the images to an LE and an RE of a user, respectively. Therefore, a user can view a 3D image by mentally combining an image of an LE and an image for an RE obtained through the retina of the two eyes of the user. The 3D image display device can be widely applied to a variety of fields requiring a 3D image such as medical treatment, game, advertisement, education, and military affairs.
Recently, as a high-quality high-definition television (HDTV) and mobile communication develop, development of a real-sense type mobile 3D display device is required. The mobile 3D display device can be embodied in cellular phones, personal digital assistants (PDAs), tablet computers, notebook computers, or portable televisions. The relative position of the mobile 3D display device can change with respect to the position of two eyes of a user in view of its characteristic. Therefore, a viewing-point tracking system tracking a viewing point and switching between an image signal for a left eye (LE) and an image signal for a right eye (RE) is required so as to prevent conversion between an image for an LE and an image for an RE.
FIG. 1 is a schematic view of a 3D display device using a viewing-point tracking system of a conventional art.
Referring to FIG. 1, the 3D display device 1 includes a screen 3 providing image signals for an RE and an LE, and a lenticular lens 5 disposed on the front of the screen 3 and separating viewing regions of the images resulted on the screen 3. The screen 3 includes a lenticular screen or a parallax barrier and separates provided image signals for an RE and an LE for each viewing region using the lenticular screen and the parallax barrier. The lenticular lens 5 separates, in a plurality of viewing points, the image signals for an LE and an RE separated by the screen 3 so that the image signals can be viewed at various positions.
Therefore, a 3D image provided from the screen 3 is viewing region-separated at the lenticular lens 5 and results in viewing regions 1 through 8. Here, the image signals for the RE are resulted on the viewing regions 1, 3, 5, and 7, and the image signals for the LE are resulted on the viewing regions 2, 4, 6, and 8.
Therefore, a user whose RE and LE are positioned in the viewing regions 1 and 2, the viewing regions 3 and 4, the viewing regions 5 and 6, and the viewing regions 7 and 8, respectively, can view a 3D image provided from the display device 1.
On the contrary, when an RE and an LE of a user are positioned in the viewing regions 2 and 3, the viewing regions 4 and 5, and the viewing regions 6 and 7, respectively, the user views the image signals for the LEs through the RE and view the image signals for the REs through the LE. That is, a user (USER 1) whose RE and LE are positioned in the viewing regions 5 and 1 respectively can view a normal 3D image properly. On the contrary, a user (USER 2) whose RE and LE are positioned in the viewing regions 4 and 5, respectively, views a 3D image whose right and left are mutually converted.
To prevent conversion of a 3D image, the 3D display device 1 includes a viewing-point tracker 7 capable of tracking an eye (e.g., a solid charge coupled device (CCD) camera or an infrared camera).
Therefore, in the case where an RE and an LE of a user are positioned in the viewing regions 5 and 6, a viewing point of a user is tracked by the viewing-point tracker 7 and image signals for an RE and image signals for an LE arranged as illustrated in FIG. 1 are provided without image-signal conversion. On the contrary, in the case where an RE and an LE of a user are positioned in the viewing regions 4 and 5, a viewing point of a user is tracked by the viewing-point tracker 7 and image signals for an RE and image signals for an LE are mutually converted and then provided to a user, so that conversion of a 3D image can be prevented.
In the case where the conventional art 3D display device adopts a CCD camera so as to track the position of a viewing point, there is a disadvantage that the CCD camera is very sensitive to light. Therefore, it is difficult to track the position of the viewing point of a user at night or in the dark inside. Also, in the case where the 3D display device adopts an infrared camera, there is a disadvantage that the infrared camera is sensitive to various light sources, other than pupils of a user. In that case, the tracking of the position of a viewing point might be disturbed due to sunlight, an infrared emitted from an incandescent electric lamp or a fluorescent lamp.
Also, the 3D display device using a CCD/infrared camera has a slow response speed compared with a tracking system of other kinds. Therefore, when rapid movement of a viewing point occurs, there is high possibility that the tracking of the viewing point fails. Use of a CCD camera having a high frame rate is required to overcome the above disadvantage, but in that case, manufacturing costs increase.
An inertia sensor such as a gyroscope, an acceleration meter, other than a camera can be adopted as the viewing-point tracker. In that case, the inertia sensor has a high frame rate and can track the position even when the viewing point moves fast. However, the inertia sensor has a low signal to noise ratio (SNR) for movement of no acceleration or slow movement, so that an error increases as time elapses.